This study is based upon the New City Catechism.
The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all. (2 Corinthians 13:14)
In contrast to neighboring nations, Israel was monotheistic (Deuteronomy 6:4-5). For God to be truly holy, He must be truly distinct from all else, which refutes any idea that other beings exist as gods with God. This conviction was carried forward into the New Testament with clarity (1 Corinthians 8:4). There is only one God. Yet something startling happened between the Old and New Testaments, which further explained who this one true God is. This event was the incarnation of Christ. Christ’s incarnation revealed to us that God is not only one, but also triune. This revelation is reflected across the New Testament.
For example, in Matthew’s account of Christ’s baptism (3:16-17) we find not only a description but an interpretation of what was witnessed: God the Son standing in the river, God the Spirit descending upon Him, and God the Father blessing Him. The Apostle John apparently agreed with Matthews interpretation of God as Triune, because he presents Christ as God (John 1:1-14; 12:41; “I Am” statements), the Spirit as God (John 3:8; 6:63), and both distinct from the Father, Who is likewise God (John 3:16; 6:35-40; 17:1-26). In the New Testament, God is still one, but He is also triune. How can God be one and yet three? He can’t be, unless there is a category distinction in how He is “one” and how He is “three.” When Scripture refers to God as singular, it is in reference to His substance. There is only one divine being. When Scripture refers to God as triune, it is in reference to His personhood. There are three divine persons. We worship one God in three persons. Notice that the distinction is between being and person – these are distinct categories.
When Scripture refers to God as singular, it is in reference to His substance. There is only one divine being. When Scripture refers to God as triune, it is in reference to His personhood. There are three divine persons.Tweet
Many New Testament passages could be studied in order to further understand God as Triune! Consider only one, for now: 2 Corinthians 13:14. Paul concludes his second letter to the church at Corinth with a customary blessing. In this blessing, he calls for “grace… love… fellowship” to be enjoyed by this local church – but from Whom will these three come? Paul seems convinced that these things come from three distinct persons: “the Lord Jesus Christ… God… the Holy Spirit.” All three are put on equal ground, implying that neither is above the other. There is distinction and equality at the same time. The Son is not the Father, the Father is not the Spirit, the Spirit is not the Son. However, all three being equal, we can say that the Son is God, the Father is God, and the Spirit is God. Paul seems to attribute Divine identity and ability to each without blending the persons together.
The distinct blessings which come from each person have to do with their operation in the redemption of God’s people. First, grace comes from the Son, for it is He Who secures our redemption in His death and intercession, providing the grounds for the eternal grace we enjoy as Christians (cf. John 16-17; Ephesians 1:3-14). Second, love comes from the Father, for it is He Who ordains and oversees our redemption through His sovereign headship within the Trinity (cf. John 3:16; 1 Corinthians 11:3). Third, fellowship comes from the Spirit, for it is He Who applies all the benefits of redemption to us – those benefits ordained by the Father and secured by the Son (cf. 1 Corinthians 3:16).
All of this may seem tedious, but I implore you to take it very seriously. First, it is part of God’s special revelation to us, and so we should strive to understand it, in so far as our creaturely minds can. Second, don’t expect the fully grasp the doctrine of God as Triune, for this would require a finite creature to grasp an infinite God – like fitting the Pacific Ocean into a cup. Third, the New Testament’s teaching on God as Triune has vast, wonderful, tangible implications for every facet of our lives, and especially redemption (as explained above). Fourth, if nothing else, study God as Triune to bask in the glory of His perfections. What an amazing, awesome God we worship.
Question: How many persons are there in God?
Answer: There are three persons in one God:
the Father, the Son, and the Holy Spirit.
 “monotheism (mon´uh-thee-iz´uhm), the belief that there is only one deity. Most major religions of the biblical world were polytheistic; they had many deities. Israel was exceptional for its emphatic recognition of one God only.” (Barr, J. . monotheism. In M. A. Powell [Ed.], The HarperCollins Bible Dictionary [Revised and Updated][Third Edition, p. 653]. New York: HarperCollins)
 Matthew more clearly articulates his understanding of God as triune at the end of his gospel, when he records Jesus’ commission to the apostles: “Go therefore and make disciples of all the nations, baptizing them in the name of the Father and the Son and the Holy Spirit,” (28:19).
 The “I Am” statements of Christ in the Gospel of John are in reference to Exodus 3 when God names Himself “I am that I am.” In these statements, Christ is equating Himself with the God Who spoke to Abraham through the burning bush. These statements are as follows: 6:48; 8:12; 10:9; 10:11; 11:25; 14:6; 15:1.
 When we refer to the Trinity as it is within the Covenant of Redemption, we utilize the term “economic trinity.” When we refer to the Trinity as it was prior to the Covenant of Redemption, we utilize the term “ontological trinity.” This distinction is not necessary for our devotional purposes here, but is important when studying and contemplating further.
 This is a fellowship primarily with God, but with tangible implications for our fellowship with one another.